My 'thoughts' on esculenta
still hold true (for me I hasten to add - am not trying to gain the
truth high ground!); the real problem is, as ever, that esculenta
has been cultivated (or at least managed) for a VERY long time and that
without some pretty robust molecular work utilizing genes to
investigate the phylogenetic as well as culton level it is exceedingly
difficult to devise a reliable taxonomy. Colocasia bicolor is
almost certainly not distinguishable from affinis.

Maybe this discussion can prompt some molecular interest in colocasia.
I can certainly see how Colocasia affinis and C. heterochroma fit
within either the species C. fallax, or something on the same branch of
the family tree. I am not familiar with C. bicolor. C. 'Illustis' and
C. 'Fontanesii' look like much more distant relatives.

Back in April 2003, you mentioned "From a taxonomic perspective I tend
to apply the respective names 1. var.antiquorum, 2. var. esculenta,
and 3. var. aquatilis." I assumed from this that C. esculenta var.
antiquorum included the cultivar that we know as 'Illustris'. Is this
still your thinking, or has new information moved your thoughts in a
different direction?

I am not saying it is 100%, all
I can say is that types plants of heterochroma and bicolor that I have
seen in China fall pretty incontrovertibly into fallax sens. lat. They
are all notable for the pencil-diameter stolons that do not branch
much, the thin-textured leaves that are often (but by not means always)
dark-variegated and the rather dull yellow to prurpe-brwon-tinged
inflorescences.

Into this stew you need to add
C. affinis which in nature is readily identifiable by always grwoing on
near-vertical mud waterfalls and river banks with flowing water and in
nature and cultivation by the very slender (almost wire-thin) much
branching stolons. Colocasia affinis is also USUALLY of much
smaller stature than fallax sens lat. although big plants of
afiinis can be larger and as robust as small-end fallax
while large end fallax can be mistaken as rather weakend esculenta.

As to mlecular analyses of this
group, as far as I am aware nothing is underway.

Say it ain't so. C. 'Illustris' is a selection of C. fallax? Are you
also saying that C. heterochroma now gets dumped into C. fallax also?
Obviously, I must have slept while the taxonomists worked. Has someone
completed the DNA-based phylogeny of colocasia yet?